Image reading apparatus and image forming apparatus

ABSTRACT

An image reading apparatus includes: an opening/closing portion configured to be rotatable around a hinge shaft; a biasing portion configured to apply a force to the opening/closing portion such that moment of the hinge shaft rotation higher than moment of the hinge shaft rotation according to self-weight of the opening/closing member is generated in a state in which the opening/closing portion is placed in a range up to a predetermined rotation angle from a closed position with respect to the apparatus main body, and moment of the hinge shaft rotation that is balanced with the moment of the hinge shaft rotation according to the self-weight of the opening/closing portion is generated in a state in which the opening/closing portion is opened more than the predetermined rotation angle; and a holding portion configured to maintain the opening/closing portion at the closed position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image reading apparatus and an imageforming apparatus including a hinge device that supports anopening/closing member such as an automatic document feeding device,which automatically sends an original to an image reading portion, to beopened or closed with respect to the apparatus main body of the imagereading apparatus or the image forming apparatus.

2. Description of the Related Art

Conventionally, in a copying machine in which an automatic documentfeeding device is mounted, in a case where an original is copied, theautomatic document feeding device disposed to be freely opened or closedwith respect to transparent glass (hereinafter, referred to as anoriginal base plate glass) disposed on the upper face of the apparatusmain body is used in a closed state. Accordingly, the automatic documentfeeding device sequentially conveys originals to the original base plateglass in which an image reading portion is placed one at a time, and theoriginals can be automatically read one by one. In addition, instead ofusing the automatic document feeding device, by opening the automaticdocument feeding device to the apparatus main body, an original may bedirectly placed on the original base plate glass so as to be read.

In the automatic document feeding device, in order to automaticallyconvey an original, many components such as various rollers and motorsare built. Accordingly, the weight of the automatic document feedingdevice is several kilograms to several tens of kilograms, and an openingor closing operation cannot be easily performed as it is. Thus,generally, an opening/closing mechanism called a hinge device used fordecreasing an operation force is included.

The hinge device has a spring built therein and applies a force in adirection opening the automatic document feeding device, in other words,a direction cancelling the weight (hereinafter, referred to as a“self-weight”) of the automatic document feeding device. Accordingly,the balance between the spring and the self-weight is set such that theautomatic document feeding device can be lifted with a weak force at thetime of opening and can be quietly closed at the time of closing.

In addition, there is an automatic document feeding device that includesa shock absorber that is an impact mitigating portion such as an oildamper in the hinge device. Since the oil damper generates a resistanceforce against the direction in which the automatic document feedingdevice is closed, there is an advantage of decreasing the closing speedof the automatic document feeding device so as to reduce a shock or asound generated in accordance with the collision thereof with theapparatus main body. Accordingly, not only the original base plateglass, a driving portion of the automatic document feeding device, andthe like are protected, but also oscillation delivered to the imageforming apparatus is reduced, whereby disturbances in an image at thetime of forming the image can be prevented.

In addition, as disclosed in Japanese Patent Laid-Open No. 3-184059, inorder to easily replace an original on the original base plate glass,even when the hand is separated from the open automatic document feedingdevice, the automatic document feeding device is set to stay at theposition (hereinafter, this state will be referred to as free stop).Furthermore, in order to maintain a state in which the automaticdocument feeding device securely lands on the original base plate glass,balance between the spring and the self-weight is set. FIGS. 17A and 17Billustrate a conventional example. FIG. 17A is a simplified view thatillustrates each opening/closing angle state, and FIG. 17B is a diagramthat represents the “magnitude relation between the spring and theself-weight” at each opening/closing angle converted into moment.

For example, a state in which the ADF (automatic document feedingdevice) is closed with respect to the original base plate glass disposedon the reader (image reading apparatus) side is represented as 0degrees, and a vertical state is represented as 90 degrees. At thistime, in a case where the opening/closing angle is in the range of 15degrees to 70 degrees, a state is formed in which the spring and theself-weight are balanced, and thus, when the automatic document feedingdevice is in the free stop state, and the hand is separated therefrom,the automatic document feeding device does not fall in accordance withthe self-weight. In addition, when the automatic document feeding deviceis opened up to 90 degrees, a case where a handle (a knob at the time ofopening or closing) is not reached by the hand at the time of closing, acase where an impact is applied to the hinge device, or the like may becaused. Thus, actually, the opening angle of the automatic documentfeeding device is configured to be limited up to 70 degrees.

Furthermore, in a case where the opening/closing angle is in the rangeof 0 degrees to 15 degrees, a state is configured to be formed in whichthe spring<the self-weight, so that the automatic document feedingdevice falls in accordance with the self-weight. Accordingly, theautomatic document feeding device is configured not to be stopped in thestate in which the automatic document feeding device is about half openwith respect to the original base plate glass. By configuring the springforce of the hinge device to be sufficiently weaker than the self-weightof the automatic document feeding device, the automatic document feedingdevice securely lands on the original base plate glass.

When the automatic document feeding device does not securely land on theoriginal base plate glass but is in a half-open state, the pressingforce for the original placed on the original base plate glass islowered, and accordingly, a defective image is generated, or a paper jamoccurs when the automatic document feeding device is used. Accordingly,generally, the self-weight is set to be stronger than the spring forceby about 2 to 3 Kgf as a whole at the position of the handle of theautomatic document feeding device, and the state in which the automaticdocument feeding device is approximately half-open is avoided.

However, in the configuration disclosed in Japanese Patent Laid-Open No.3-184059 or illustrated in FIGS. 17A and 17B, the state of closing theoriginal base plate glass is assured by setting the self-weight of theautomatic document feeding device to be larger than the spring force,and accordingly, a force of about 2 to 3 Kgf is necessary for openingthe automatic document feeding device. Thus, there is a limit on thedecrease in the opening/closing force.

SUMMARY OF THE INVENTION

It is desirable to improve the user's operability.

According to the present invention, there is provided an image readingapparatus including: an apparatus main body; an opening/closing portionconfigured to be rotatable with respect to the main body, around a hingeshaft; a biasing portion configured to apply a force to theopening/closing portion in an opening direction to generate a moment ofthe hinge shaft rotation higher than the moment of the hinge shaftrotation according to self-weight of the opening/closing portion, in astate in which the opening/closing portion is in a range up to apredetermined rotation angle from a closed position with respect to theapparatus main body, and to generate a moment of the hinge shaftrotation that is substantially balanced with the moment of the hingeshaft rotation according to the self-weight of the opening/closingportion, in a state in which the opening/closing portion is opened morethan the predetermined rotation angle; and a holding portion configuredto maintain the opening/closing portion at the closed position.

Further features of the present invention will become apparent from thefollowing description of illustrative embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an external view of an image forming apparatus.

FIG. 2 is a schematic cross-sectional view of an image readingapparatus.

FIG. 3 is a block diagram of the circuit configuration and an imagesignal controller of the image reading apparatus.

FIG. 4 is a control block diagram of an image processing portion.

FIG. 5 is a diagram that illustrates relation between the self-weight ofan automatic document feeding device and a spring force of a hingedevice.

FIG. 6 is a cross-sectional view that illustrates the configuration of ahinge device according to a first embodiment.

FIG. 7 is a cross-sectional view that illustrates a free stop state ofthe hinge device according to the first embodiment.

FIG. 8 is a cross-sectional view that illustrates a tip-up state of thehinge device according to the first embodiment.

FIG. 9A is a diagram that illustrates the configuration of a handleportion, and FIG. 9B is an enlarged view of a main part of the handleportion.

FIGS. 10A and 10B are diagrams that illustrate a holding portionaccording to the first embodiment (the configuration of a magnet).

FIG. 11 is a cross-sectional view that illustrates a closed state of ahinge device according to a second embodiment.

FIG. 12 is a cross-sectional view that illustrates an open state of thehinge device according to the second embodiment.

FIG. 13 is a diagram that illustrates a holding portion according to thesecond embodiment (the configuration of a latch).

FIGS. 14A and 14B are cross-sectional views that illustrate theconfiguration of a hinge device according to a third embodiment.

FIG. 15 is a diagram that illustrates relation between the self-weightof the automatic document feeding device and the spring force of thehinge device at the time of moving an adjustment portion to a lower sideof the axis.

FIG. 16 is a diagram that illustrates relation between the self-weightof the automatic document feeding device and the spring force of thehinge device at the time of moving the adjustment portion to an upperside of the axis.

FIGS. 17A and 17B are diagrams that illustrate a conventional example.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, illustrative embodiments of the present invention will bedescribed in detail with reference to the drawings. However, thedimension, the material, and the shape of each constituent componentdescribed in the following embodiments and relative arrangements and thelike thereof should be appropriately changed in accordance with theconfiguration and various conditions of an apparatus to which thepresent invention is applied. Accordingly, unless otherwise specified,the scope of the present invention is not intended to be limitedthereto.

First Embodiment

Hereinafter, an image forming apparatus including a hinge deviceaccording to a first embodiment will be described with reference toFIGS. 1 to 10B. Here, as the image forming apparatus including the hingedevice, a copying machine as an image forming apparatus including anautomatic document feeding device configured to be opened or closed isillustrated as an example.

FIG. 1 is a schematic configuration diagram of the image formingapparatus including the automatic document feeding device configured tobe opened or closed.

An image forming apparatus 1 (hereinafter, referred to as an apparatusmain body) illustrated in FIG. 1 is configured by: a main body 100thereof; a sheet cassette 33 that is mounted below the main body 100;and an automatic document feeding device (opening/closing member) 2 thatis mounted on the upper face of the main body 100.

In the main body 100, an image forming portion is arranged at anapproximately center portion thereof, and a feed portion is located onthe lower side thereof. In addition, an image reading portion includinga CCD or the like is arranged in the uppermost portion of the main body.In addition, a space is arranged between the image reading portion andthe image forming portion so as to form a discharge space portion 34.

In the main body 100, the image forming portion forms an image on asheet. The image forming portion is configured as a print engineemploying a conventionally known electrophotographic system and has alaser writing portion, an electrophotographic process portion, a fixingportion, and the like, which are not illustrated in the figure, builttherein. The feed portion includes the sheet cassette 33 and supplies asheet to the image forming portion.

The image reading portion reads image information of an original. In theimage reading portion, as illustrated in FIG. 2, a casing frame 102 isarranged, and, on the upper face thereof, a transparent glass 101(hereinafter, referred to as an original base plate glass) is arranged.In addition, on the lower side thereof, an image reading unit (scanunit) 103 is arranged.

The automatic document feeding device 2 is mounted in the casing frame102 disposed in the upper part of the main body 100 by a hinge device(hinge mechanism) disposed on the rear side of the apparatus and issupported by the upper face of the apparatus main body to be freelyrotatable so as to open or close the original base plate glass 101disposed on the upper face of the image reading portion. In theautomatic document feeding device 2, a bundle of originals (notillustrated in the figure) set on an original base plate 31 is conveyedfrom the upper side to the original base plate glass 101 one at a time.Then, after the originals are read and scanned by the image readingportion, the originals are sequentially discharged to an originaldischarge plate 32.

When a copy is made without automatic feed, or when a book, a notebook,or the like is copied, the automatic document feeding device 2 may beused as a platen.

Next, a schematic configuration of an image reading apparatus accordingto an embodiment of the present invention will be described withreference to FIG. 2.

As illustrated in FIG. 2, an original base plate glass 101 is anoriginal placement portion in which an original is placed, a casingframe 102 supports the original base plate glass (101), and an imagereading unit (scan unit) 103 scans the original. In addition, a belt 104moves the image reading unit (scan unit), and a pulley 105 drives thebelt, and a motor 106 rotates the pulley.

The image reading unit 103 is configured by: a lighting unit 108 thatlights up an original; reflecting mirrors 109, 110, and 111 that guidelight reflected on the original; a lens 112 that performs imageformation of light; a CCD 113 that performs photoelectric conversion ofimaged light and reads a resultant signal; and an electrical substrate114 that drives the CCD. These components are integrally mounted on acarriage frame 107 as scan units.

In such a configuration, when image information of an original is read,the image reading unit 103 scans the original using the pulley 105 andthe belt 104 by rotating the motor 106 while the original placed on theoriginal base plate glass 101 is illuminated by the lighting unit 108.The light hitting the original diffuses from the original face, isguided to the lens 112 by the reflecting mirrors 109, 110, and 111, andis imaged by the guide lens 112. Thereafter, the imaged light isphotoelectrically converted into an electric signal by the CCD 113, andthe signal is electrically read.

Units 301, 302, and 303 of a white reference member provide whitereference data used for shading correction, and, before the image of anoriginal is read, the image reading unit (scan unit) 103 is moved up tothis position, and shading correction is made.

In addition, a moving original reading glass (transparent glass) 115 isarranged and is located at a reading position in a case where theautomatic document feeding device 2 is mounted. An original fed from afeed portion (not illustrated in the figure) of the automatic documentfeeding device 2 passes through the moving original reading glass 115,and image information of the original is read by the image reading unit103 that stops and is positioned below the moving original reading glass115. Furthermore, an inclined guide 116 is a guide member used forlifting the front end of the original passing through the movingoriginal reading glass 115 and guiding the original to the inside of theautomatic document feeding device again.

Next, the shading correction will be described with reference to FIGS. 2and 4.

The shading correction performed by the image reading unit (scan unit)103 is performed, as illustrated in FIG. 2, as the image reading unit(scan unit) 103 moves below a shading white board 302 that is installedto be parallel with the original base plate glass 101.

Then, as illustrated in FIG. 4, based on the acquired image data, theimage processing portion 210 performs various corrections such as asensitivity correction using an analog signal processing portion 211.Thereafter, in the image processing portion 210, an A/D conversionportion 212 converts the signal into a digital image signal, and variouscorrections are made for the digital image signal by a gain controlportion 213, a shading correction portion 214, a tone control portion215, and the like. Thereafter, the image data is transferred to an imageforming apparatus (not illustrated in the figure) or the like as digitaldata.

Next, a block diagram relating to the control process of theabove-described apparatus will be described with reference to FIG. 3.

A CPU circuit portion 400 includes a CPU 401 and controls a readingcontroller 201, an image signal controller 405, and an external I/F 406in accordance with the setting of an operation portion 404 based on aprogram stored in ROM 402. RAM 403 is used as an area that temporarilystores control data and as a work area of a calculation processaccompanied with the control process. The external I/F 406 is aninterface from a computer 407 and develops print data into an image andoutputs the image to the image signal controller 405.

The image processing portion 410 performs an image correction process oran editing process according to the setting of the operation portion. Aline memory 411 performs a mirror image process for changing the mainscanning direction and the like. The image stored in the line memory 411is output through a page memory 412. A hard disk 413 is used as isnecessary when the page sequence is changed or the like.

Next, the configurations of the hinge device, the holding portion, andthe handle portion according to this embodiment will be described withreference to FIGS. 5 to 10B.

FIG. 5 is a diagram that illustrates magnitude relation between theself-weight of the automatic document feeding device 2 and the springforce of the hinge device by using moment in a case where the hingedevice according to this embodiment is used. The horizontal axisrepresents the rotation angle (opening/closing angle) of the automaticdocument feeding device 2 with respect to the original base plate glass101, and the vertical axis represents the moment (a biasing force or aspring force). In the figure, a dotted line represents moment accordingto the self-weight of the automatic document feeding device 2, and asolid line represents moment according to the spring force of the hingedevice. In a range from the closed state to a predetermined rotationangle θ1, the moment according to the spring force of the hinge deviceis configured to be higher than the moment according to the self-weightof the automatic document feeding device 2. In a range of a rotationangle θ2 for which the automatic document feeding device is open morethan the predetermined rotation angle θ1, the moment according to theself-weight of the automatic document feeding device 2 and the momentaccording to the spring force of the hinge device are set to bebalanced. Accordingly, when the automatic document feeding device 2 isopen, up to the predetermined rotation angle θ1, the automatic documentfeeding device 2 can be opened with a light force, and, in a state inwhich the automatic document feeding device is open more than thepredetermined rotation angle θ1, the automatic document feeding device 2can be stopped at a position desired by a user.

FIG. 6 is a cross-sectional view of the hinge device 10 according tothis embodiment. The automatic document feeding device 2 is covered witha cover 3 that is an exterior configuring member. The automatic documentfeeding device 2 is attached to the apparatus main body 1 (casing frame102) through the hinge device 10 so as to be opened or closed withrespect to the original base plate glass 101. The hinge device 10supports the automatic document feeding device 2, which is anopening/closing member, to be opened or closed with respect to thecasing frame 102 that is the main body frame of the apparatus main body1.

The hinge device 10 includes: a hinge base 14 that is a first attachmentmember; a hinge arm 7 that configures a second attachment member; a liftarm 4; and a hinge shaft 13 that is connected to the hinge base 14 so asto allow the hinge arm 7 to be rotatable with respect to the hinge base.In addition, the hinge device 10 includes a biasing portion that isexpanded or contracted in accordance with the rotation angle of theautomatic document feeding device with respect to the apparatus mainbody 1 and applies a force to the automatic document feeding device 2 inan opening direction. The biasing portion is disposed between the hingebase 14 and the hinge arm 7. Here, the biasing portion includes acompression spring 16 that is a first elastic member and a compressionspring 12 that is a second elastic member and further includes a lowerspring shaft portion 6, a lower spring holder portion 15, a upper springholder portion 17, and a upper spring shaft portion 18.

The hinge shaft 13 is supported by the hinge base 14 that is the firstattachment member, and the hinge base 14 is fixed to the apparatus mainbody 1 (casing frame 102). In addition, since the hinge shaft 13 axiallysupports the hinge arm 7 configuring the second attachment member, thehinge arm 7 is rotatable with respect to the hinge base 14.

In addition, since the hinge arm 7 configuring the second attachmentmember supports the lift arm 4 configuring the second attachment memberthrough the lift shaft 5, the lift arm 4 is rotatable with respect tothe hinge arm 7. While a height adjustment screw 8 is fixed to the liftarm 4, the height adjustment screw 8 is freely movable back and forth,and the front end abuts a part of the hinge arm 7, whereby the height ofthe automatic document feeding device 2 with respect to the originalbase plate glass 101 can be adjusted. The lift arm 4 is fixed to theautomatic document feeding device 2 (cover 3).

The lift arm 4 supports the upper spring shaft portion 18. The upperspring shaft portion 18 axially supports the upper spring holder portion17. The upper spring holder portion 17 holds one end portion of each oneof the compression springs 12 and 16, and the lower spring holderportion 15 is arranged on the opposing side so as to hold the other endof each one of the compression springs 12 and 16. The lower springholder portion 15 is axially supported by the lower spring shaft portion6. The lower spring shaft portion 6 is fixed to the hinge base 14.Accordingly, a gap between the upper spring shaft portion 18 and thelower spring shaft portion 6 changes in the opening/closing operation ofthe automatic document feeding device 2, and the compression springs 12and 16 are expanded and contracted in accordance therewith.

FIGS. 7 and 8 are cross-sectional views of the hinge device 10 in a casewhere the automatic document feeding device 2 is open up to angles θ2and θ1. By opening the automatic document feeding device 2, a gapbetween the lower spring shaft portion 6 and the upper spring shaftportion 18 increases, and the reaction forces of the compression springs12 and 16 are received, whereby a gap between the upper spring holderportion 17 and the lower spring holder portion 15 increases inaccordance therewith.

As illustrated in FIGS. 7 and 8, in a case where the rotation angle(opening/closing angle) is any one of θ1 and θ2, both ends of thecompression spring 16 that is the first elastic member are in contactwith the upper spring holder portion 17 and the lower spring holderportion 15. Accordingly, in the case where the rotation angle is any oneof θ1 and θ2, the compression spring 16 acts as a biasing force forapplying a force to the automatic document feeding device 2 in theopening direction.

In contrast to this, up to the predetermined rotation angle θ1 from thestate in which the automatic document feeding device 2 is closed withrespect to the apparatus main body 1, both ends of the compressionspring 12 that is the second elastic member are in contact with theupper spring holder portion 17 and the lower spring holder portion 15(see FIG. 8). However, at the rotation angle θ2 for which a state isformed in which the automatic document feeding device is open more thanthe predetermined rotation angle θ1, only the compression spring 16 isin contact with the upper spring holder portion 17 and the lower springholder portion 15, and one end portion of the compression spring 12 isconfigured to be separated from the upper spring holder portion 17 (seeFIG. 7).

In other words, as illustrated in FIG. 8, up to the rotation angle θ1from the closed state, the compression spring 12 acts together with thecompression spring 16, and the moment of the hinge shaft rotationaccording to the hinge device 10 is higher than the moment according tothe self-weight of the automatic document feeding device 2. Accordingly,between the closed state of the automatic document feeding device 2 andup to the rotation angle θ1, the automatic document feeding device 2 isopened in accordance with the forces of the compression springs 16 and12. Accordingly, up to the rotation angle θ1 from the closed state, theopening/closing force of the automatic document feeding device 2 can bereduced.

On the other hand, as illustrated in FIG. 7, at the rotation angle θ2for which a state is formed in which the automatic document feedingdevice 2 is open more than the rotation angle θ1, the compression spring12 does not act, but only the compression spring 16 acts, andaccordingly, a state is formed in which the moment of the hinge shaftrotation according to the hinge device 10 (compression spring 16) andthe moment according to the self-weight of the automatic documentfeeding device 2 are balanced. Accordingly, in the range of the rotationangle θ2, the automatic document feeding device 2 can be freely stoppedat a free angle. Here, the state in which the moment according to thespring force of the compression spring 16 of the hinge device and themoment according to the self-weight of the automatic document feedingdevice 2 are balanced not only represents a state in which themagnitudes of the moments are precisely the same but also includes thefollowing state. In other words, a state in which a force causing theautomatic document feeding device 2 to rotate in accordance with adifference between the moment according to the spring force of thecompression spring 16 and the moment according to the self-weight of theautomatic document feeding device 2 is less than frictional resistancerelating to the rotation of the automatic document feeding device 2, andthe state in which the automatic document feeding device 2 stops unlessan external force is added to the automatic document feeding device 2 isalso the state in which the two moments are balanced.

FIGS. 9A and 9B are diagrams in which a portion near the handle portion50 positioned at the approximately center portion of the front face ofthe automatic document feeding device 2 is extracted. FIG. 9A is a frontview of a portion near the handle portion, and FIG. 9B is an enlargedview of the holding portion. FIGS. 10A and 10B are cross-sectional viewstaken along line A-A represented in FIG. 9A. FIG. 10A is a diagram thatillustrates a state (closed state) in which the automatic documentfeeding device 2 is held by the holding portion with respect to theapparatus main body (casing frame 102), and FIG. 10B is a diagram thatillustrates a state in which the holding portion is released.

The handle portion 50 is used for opening the automatic document feedingdevice 2 and is disposed at the approximately center portion of thefront face of the automatic document feeding device 2. The handleportion 50 includes a handle 51 that serves as a grip when a user opensor closes the automatic document feeding device 2. The handle 51 isattached to the automatic document feeding device 2 to be rotatable withrespect to the automatic document feeding device using a rotation shaft56. As illustrated in FIG. 10B, the rotated handle 51 is configured tobe returned to the original position (a position illustrated in FIG.10A) by a return spring 57.

At both ends of the handle 51, magnets (magnet catchers) 52 and 53 thatconfigure the holding portion are disposed. In the apparatus main body 1(the casing frame 102) that is on the opposite side of the magnets 52and 53, magnetic bodies 54 and 55 such as metal plates that configurethe holding portion are disposed. The automatic document feeding device2 maintains the closed state with respect to the apparatus main body 1(the casing frame 102) depending on a magnetic coupling force accordingto the magnets 52 and 53 and the magnetic bodies 54 and 55 as theholding portions. The reason for disposing the holding portions on bothend sides with the handle 51 being nipped therebetween is to maintainthe automatic document feeding device 2 to be parallel to the apparatusmain body 1 (the casing frame 102 and the original base plate glass101). Although not illustrated in the figure, by arranging a unit thatadjusts the attaching positions (heights) of the magnets 52 and 53, theparallel state can be adjusted.

When the automatic document feeding device 2 is opened or closed, asillustrated in FIG. 10B, the handle 51 is pressed in the direction ofthe arrow B. Accordingly, the handle 51 rotates around the rotationshaft 56, and the magnets 52 and 53 attached to the handle 51 areseparated away from the magnetic bodies 54 and 55 attached to theapparatus main body 1 (the casing frame 102), whereby the magneticcoupling force is released. When the magnetic coupling force isreleased, the automatic document feeding device 2 can be lifted up tothe position of the rotation angle θ1 by using only the spring force ofthe hinge device 10 (the compression springs 12 and 16).

Here, the positions of the handle 51, the holding portions 52 to 55, andthe rotation shaft 56 will be described. As described above, in order tosecurely maintain the automatic document feeding device 2 with respectto the apparatus main body 1 (the casing frame 102), a predeterminedforce (for example, a force of about 2 to 3 Kgf as a whole) is necessaryat the position of the handle 51. In other words, also in thisembodiment, a magnetic coupling force of about 2 to 3 Kgf is necessary.In this embodiment, as illustrated in FIGS. 10A and 10B, the magnets 52and 53 and the magnetic bodies 54 and 55 configuring the holdingportions are arranged between the handle 51 and the rotation shaft 56,and these holding portions are arranged as close to the side of therotation shaft 56. Accordingly, by using the principle of leverage, theholding force (magnetic coupling force) according to the holdingportions can be easily released.

In this embodiment, as the holding portions, while the magnets 52 and 53are disposed on the side of the automatic document feeding device 2, andthe magnetic bodies 54 and 55 are disposed on the side of the apparatusmain body 1 (the casing frame 102), the holding portions may berespectively arranged on opposite sides. In other words, the holdingportions may have a configuration in which the magnets 52 and 53 aredisposed on the side of one of the apparatus main body 1 and theautomatic document feeding device 2, the magnetic bodies 54 and 55 aredisposed on the side of the other, and the automatic document feedingdevice is maintained to be in the closed state (position) with respectto the apparatus main body in accordance with the magnetic couplingforce.

Here, while two magnets and two magnetic bodies have been described tobe arranged on both sides of the handle 51, the numbers of the magnetsand the magnetic bodies are not limited to two. In addition, while thehandle 51 has been described as being configured to be rotated using therotation shaft 56, the configuration is not limited thereto as long asthe holding portions can be retracted.

In addition, in this embodiment, while the handle portion 50 is disposedon the side of the automatic document feeding device 2, the handleportion 50 may be disposed on the side of the apparatus main body 1, anda configuration may be employed in which the holding state according tothe holding portions can be released.

According to this embodiment, in the range up to the predeterminedrotation angle θ1 from the closed state of the automatic documentfeeding device 2 with respect to the apparatus main body 1, the moment(biasing force) of the hinge shaft rotation according to the biasingportion is higher than the moment of the hinge shaft rotation accordingto the self-weight of the automatic document feeding device 2.Accordingly, the automatic document feeding device 2 that is theopening/closing member can be opened using a weak force.

In addition, in the range of the rotation angle θ2 for which theautomatic document feeding device 2 is open with respect to theapparatus main body 1 more than the case of the predetermined rotationangle θ1, the moment (biasing force) of the hinge shaft rotationaccording to the biasing portion and the moment of the hinge shaftrotation according to the self-weight of the automatic document feedingdevice 2 are balanced. Accordingly, the automatic document feedingdevice 2 can be freely stopped at an arbitrary position, whereby theuser's operability can be improved.

In this embodiment, in order to maintain the balanced state, asillustrated in FIG. 5, the moment of the hinge shaft rotation accordingto the biasing portion is set to be slightly higher than the moment ofthe hinge shaft rotation according to the self-weight of the automaticdocument feeding device 2. The reason for this is that a change in themoment due to a variation of the self-weight of the automatic documentfeeding device 2 has been considered. In addition, in a case where thefrictional resistance occurring when the hinge device rotates is high,the moment of the hinge shaft rotation according to the biasing portionmay be set to be equal to or slightly lower than the moment of the hingeshaft rotation according to the self-weight of the automatic documentfeeding device 2.

Second Embodiment

Next, a hinge device and holding portions according to a secondembodiment will be described with reference to FIGS. 11 to 13. Sinceconfigurations other than the hinge device and the holding portions arethe same as those of the above-described embodiment, the same referencesign is assigned to portions having the same function and the sameconfiguration, and description thereof will not be presented.

FIGS. 11 and 12 are cross-sectional views of the hinge device 81according to this embodiment. The hinge device 81 includes first andsecond attachment members 83 and 84 that are connected to a rotationshaft (hinge shaft) 82 so as to be relatively freely rotatable and acompression spring 85 that is an elastic member expanding or contractingin accordance with the rotation of the first and second attachmentmembers 83 and 84. In addition, a cam member 86 is fixed to the secondattachment member 84. An abutting portion 87 a of a housing 87 housingthe compression spring 85 that is one end of the elastic member isbrought into contact with cam faces 86 a and 86 b of the cam member 86so as to slide.

The first attachment member 83 configuring the hinge device 81 isfastened and fixed to the automatic document feeding device 2 by afastening portion such as a screw not illustrated in the figure androtates around the rotation shaft 82 together with the automaticdocument feeding device 2. In addition, the second attachment member 84that is connected to the first attachment member 83 through the rotationshaft 82 is fixed to the apparatus main body 1 (the casing frame 102).

One end of the compression spring 85 that is the elastic memberexpanding or contracting in accordance with the rotation of the firstand second attachment members 83 and 84 abuts the cam face of the cammember 86 fixed to the second attachment member 84 through the housing87 so as to be in contact therewith and slide. In addition, the otherend of the cam member 86 is locked into a shaft 83 a fixed to the firstattachment member 83 through a housing 88 so as to be fixed thereto.

The shape of the cam face of the cam member 86 is appropriately set inconsideration of the moment according to the self-weight of theautomatic document feeding device 2 around the rotation shaft 82 and adesired opening/closing operation condition such as “a specific angle atwhich the automatic document feeding device stops” or “a specific anglefrom which the automatic document feeding device falls in accordancewith the self-weight”. In this embodiment, the cam face is divided intotwo areas including a first cam face 86 a as a first area and a secondcam face 86 b as a second area, and the cam faces are set so as tosatisfy the following opening/closing operation condition.

The first cam face (first area) 86 a of the cam member 86 is in contactwith the abutting portion 87 a of the housing 87 in the range of therotation angles 0 degrees to β1 (corresponding to the rotation angle θ1of the first embodiment). This first cam face 86 a causes the momentaccording to the spring force of the hinge device higher than the momentaccording to the self-weight of the automatic document feeding device 2to be generated. Accordingly, when the automatic document feeding device2 is opened, the opening operation can be performed using a weak force.

The second cam face (second area) 86 b of the cam member 86 is broughtinto contact with the abutting portion 87 a of the housing 87 in therange of the rotation angle β2 for which the automatic document feedingdevice 2 is open more than the case of the rotation angle β1. Thissecond cam face 86 b is in a state in which the moment according to theself-weight of the automatic document feeding device 2 and the momentaccording to the spring force of the hinge device are balanced.Accordingly, the automatic document feeding device 2 can be stopped at aposition desired by the user.

FIGS. 13A and 13B illustrates the configuration of the holding portion.The configuration of the handle portion is the same as that of the firstembodiment described above, and only a part that is different from thatof the first embodiment will be described. First, a locking projection61 is a hook member disposed on the side of the automatic documentfeeding device 2, and a pin 63 is a hook supporting portion disposed onthe side of the apparatus main body 1 (the casing frame 102). Thelocking projection 61 configuring this holding portion is fixed to therotation shaft 62, and a handle 51 (the same configuration as that ofthe first embodiment and thus is not illustrated in the figure) isadditionally fixed to the rotation shaft 62. In other words, aconfiguration is employed in which, similar to the first embodiment, bypressing the handle 51 in the direction of arrow B illustrated in FIG.10B, as illustrated in FIG. 13B, the rotation shaft 62 and the lockingprojection 61 are rotated so as to release a connection with the pin 63.When the connection is released, the automatic document feeding device 2can be lifted using only the spring force of the hinge device up to aposition of the rotation angle β1. Thereafter, the locking projection 61is returned to the original position by the spring 64. The lockingprojection 61 and the pin 63, similar to the first embodiment describedabove, in order to hold the automatic document feeding device 2 parallelto the apparatus main body 1 (the casing frame 102 and the original baseplate glass 101), are disposed on both sides of the handle 51 (notillustrated in the figure).

In this embodiment, while the locking projection 61 (hook member) isdisposed on the side of the automatic document feeding device 2, and thepin 63 (hook supporting portion) is disposed on the side of theapparatus main body 1 (the casing frame 102) as the holding portions,the hook member and the hook supporting portion may be respectivelyarranged on the opposite sides thereof. In other words, a configurationof the holding portions may be employed in which the hook member isdisposed on the side of one of the apparatus main body 1 and theautomatic document feeding device 2, the hook supporting portion isdisposed on the side of the other, and the automatic document feedingdevice is maintained to be in the closed state with respect to theapparatus main body by locking the hook member into the hook supportingportion.

In addition, while two locking projections 61 and two pins 63configuring the holding portions are arranged on both sides of thehandle 51, the numbers of the locking projections and the pins are notlimited thereto.

In the first and second embodiments, instead of a configuration in whichthe automatic document feeding device 2 is caused to fall in accordancewith the self-weight with respect to the apparatus main body (the casingframe 102), the configuration is employed in which the automaticdocument feeding device 2 is closed by the user. Accordingly, a shockabsorber used in the hinge of the conventional example, in other words,an impact mitigating portion such as an oil damper is not necessary,which can contribute to reduced costs.

Also in this embodiment, in the range up to the predetermined rotationangle β1 from the closed state of the automatic document feeding device2 with respect to the apparatus main body 1, the moment (biasing force)of the hinge shaft rotation according to the biasing portion is higherthan the moment of the hinge shaft rotation according to the self-weightof the automatic document feeding device 2. Accordingly, the automaticdocument feeding device 2 that is the opening/closing member can beopened easily.

In addition, in the range of the rotation angle β2 for which theautomatic document feeding device 2 is open with respect to theapparatus main body 1 more than the case of the predetermined rotationangle β1, the moment (biasing force) of the hinge shaft rotationaccording to the biasing portion and the moment of the hinge shaftrotation according to the self-weight of the automatic document feedingdevice are balanced. Accordingly, the automatic document feeding device2 can be freely stopped at an arbitrary position, whereby the user'soperability can be improved.

Third Embodiment

Next, an adjustment portion of a hinge device according to a thirdembodiment will be described with reference to FIGS. 14A to 16. Sinceconfigurations other than the adjustment portion are the same as thoseof the above-described first embodiment, the same reference sign isassigned to portions having the same function and the sameconfiguration, and description thereof will not be presented.

In the third embodiment, in addition to the configuration of the firstembodiment described above, an adjustment portion that can adjust theposition of the compression spring 12 configuring the hinge device inthe expanding/contracting direction is included. Since configurationsother than the adjustment portion are the same as those of theabove-described first embodiment, the same reference sign is assigned toportions having the same function and the same configuration, anddescription thereof will not be presented.

In this embodiment, as illustrated in FIGS. 14A and 14B, an adjustmentportion 19 that can adjust the position (height) of a compression spring12 in the expanding/contracting direction is disposed on the side of alower spring holder portion 15 so as to be in contact with thecompression spring (second elastic member) 12 of a hinge device 10. Asillustrated in FIG. 14B, the adjustment portion 19 has cut screw threadson the outer circumference and can move the position of the compressionspring (second elastic member) 12 in the expanding/contracting directionby using an adjustment tool (not illustrated in the figure). By changingthe position of the compression spring (second elastic member) 12 in theexpanding/contracting direction using the adjustment portion 19, adistance 71 between the end portion of the compression spring (secondelastic member) 12 illustrated in FIG. 7 and the upper spring holderportion 17 changes. Accordingly, the range up to the predeterminedrotation angle θ1 in which the compression spring (second elasticmember) 12 starts to act when the automatic document feeding device 2 isclosed can be changed.

For example, when the adjustment portion 19 is caused to act in thedirection of a lower spring shaft portion 6, the compression spring 12also moves in the direction of the lower spring shaft portion 6.Accordingly, a distance 71 between the end portion of the compressionspring 12 and a upper spring holder portion 17 increases, and therefore,as illustrated in FIG. 15, the compression spring 12 starts to act at arotation angle θ3 that is smaller than the rotation angle θ1 (see FIG.5) before the adjustment. In this embodiment, while the distance 71between the compression spring 12 and the upper spring holder portion 17is increased by moving the compression spring 12 in the direction of thelower spring shaft portion 6, the same advantage can be acquired byarranging the adjustment portion on the side of the upper spring shaftportion 18 and positioning the upper spring holder portion 17 to be farfrom the compression spring 12.

In addition, for example, when the adjustment portion 19 is caused toact in the direction of the upper spring shaft portion 18, thecompression spring 12 also moves in the direction of the upper springshaft portion 18. Accordingly, the distance 71 between the end portionof the compression spring 12 and the upper spring holder portion 17decreases, and therefore, as illustrated in FIG. 16, the compressionspring 12 starts to act at a rotation angle θ4 that is larger than therotation angle θ1 (see FIG. 5) before the adjustment. In thisembodiment, while the distance 71 between the compression spring 12 andthe upper spring holder portion 17 is decreased by moving thecompression spring 12 in the direction of the lower spring shaft portion6, the same advantage can be acquired by arranging the adjustmentportion on the side of the upper spring shaft portion 18 and approachingthe upper spring holder portion 17 to the side of the compression spring12.

As described above, by disposing the adjustment portion 19 adjusting theposition of the compression spring 12 configuring the hinge device inthe expanding/contracting direction, the range up to the predeterminedrotation angle in which the compression spring (second elastic member)12 starts to act when the automatic document feeding device 2 is closedcan be changed.

In addition, in the above-described embodiments, while the hinge deviceof the image forming apparatus has been described as an example as thehinge device that supports the opening/closing member to be opened orclosed with respect to the apparatus main body, the present invention isnot limited thereto. Thus, the hinge device may be a hinge device of animage reading apparatus such as a scanner. Furthermore, in theabove-described embodiments, while the copying machine has beendescribed as an example of the image forming apparatus, the presentinvention is not limited thereto. For example, the image formingapparatus may be another image forming apparatus such as a facsimiledevice or another image forming apparatus such as a multifunctionapparatus combining such functions. By applying the present invention toa hinge device of the image forming apparatus or the image readingapparatus, the same advantages can be acquired.

While the present invention has been described with reference toillustrative embodiments, it is to be understood that the invention isnot limited to the disclosed illustrative embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all modifications, equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2013-124897, filed Jun. 13, 2013, which is hereby incorporated byreference herein in its entirety.

1-19. (canceled)
 20. An image reading apparatus comprising: an apparatusmain body including an image reading portion; a rotating portionconfigured to be rotatable around a shaft with respect to the apparatusmain body, the rotating portion capable of being placed at a firstposition, a second position where a rotation angle is more than that atthe first position, and a third position where the rotation angle ismore than that at the second position; a holding portion configured tomaintain the rotating portion at the first position; and a biasingportion configured to apply a force to move the rotating portion fromthe first position to the second position when the maintaining of therotating portion at the first position by the holding portion isreleased.
 21. The image reading apparatus according to claim 20, whereinthe biasing portion includes a first elastic member and a second elasticmember, wherein the first elastic member applies a force to the rotatingportion and the second elastic member does not apply a force to therotating portion when the rotating portion is placed in a range from thesecond position to the third position.
 22. The image reading apparatusaccording to claim 21, wherein the biasing portion includes anadjustment portion configured to adjust the rotation angle of the secondposition by changing a position of the second elastic member in anexpanding/contracting direction.
 23. The image reading apparatusaccording to claim 20, wherein the biasing portion includes: an elasticmember configured to apply a force to the rotating portion in an openingdirection; a housing configured to house the elastic member; and a cammember having first and second cam faces configured to be brought intocontact with the housing, wherein, in a state in which the rotatingportion is placed in a range from the first position to the secondposition, the housing abuts the first cam face of the cam member so thatthe rotating portion rotates in the opening direction, and wherein, in astate in which the rotating portion is placed in a range from the secondposition to the third position, the housing abuts the second cam face ofthe cam member so that the rotating portion stops at a predeterminedposition.
 24. The image reading apparatus according to claim 20, whereinthe holding portion includes: a magnet that is disposed on one of theapparatus main body and the rotating portion; and a magnetic bodydisposed on the other one of the apparatus main body and the rotatingportion, wherein the holding portion maintains the rotating portion atthe first position with respect to the apparatus main body using amagnetic coupling force.
 25. The image reading apparatus according toclaim 20, further comprising: a supporting portion including the biasingportion and configured to support the rotating portion such that therotating portion is capable of being placed at the first position, thesecond position, and the third position, wherein the supporting portionsupports the rotating portion to be stoppable when the rotating portionis placed at the third position.
 26. The image reading apparatusaccording to claim 20, wherein, at the first position, the rotatingportion closes an original placement portion arranged above the imagereading portion.
 27. The image reading apparatus according to claim 20,wherein the rotating portion is a sheet feeding device that sends asheet to the image reading portion.
 28. An image reading apparatuscomprising: an apparatus main body including an image reading portion; arotating portion configured to be rotatable around a shaft with respectto the apparatus main body, the rotating portion capable of being placedat a first position, a second position where a rotation angle is morethan that at the first position, and a third position where the rotationangle is more than that at the second position; a holding portionconfigured to maintain the rotating portion at the first position; afirst biasing portion configured to apply a force to the rotatingportion such that the rotating portion is stoppable at a predeterminedposition, in a state in which the rotating portion is placed in a rangefrom the second position to the third position; and a second biasingportion configured to apply a force to move the rotating portion fromthe first position to the second position when the maintaining of therotating portion at the first position by the holding portion isreleased.
 29. The image reading apparatus according to claim 28, furthercomprising an adjustment portion configured to adjust the predeterminedrotation angle by changing a position of the second biasing portion inan expanding/contracting direction.
 30. (canceled)
 31. The image readingapparatus according to claim 28, wherein the holding portion includes: amagnet that is disposed on one of the apparatus main body and therotating portion; and a magnetic body disposed on the other one of theapparatus main body and the rotating portion, wherein the holdingportion maintains the rotating portion at the first position withrespect to the apparatus main body using a magnetic coupling force. 32.The image reading apparatus according to claim 28, further comprising: asupporting portion configured to support the rotating portion such thatthe rotating portion is capable of being placed at the first position,the second position, and the third position, wherein the supportingportion supports the rotating portion to be stoppable when the rotatingportion is placed at the third position.
 33. The image reading apparatusaccording to claim 28, wherein, at the first position, the rotatingportion closes an original placement portion arranged above the imagereading portion.
 34. The image reading apparatus according to claim 28,wherein the rotating portion is a sheet feeding device that sends asheet to the image reading portion.
 35. An image forming apparatuscomprising: an image forming portion configured to form an image on arecording medium; an apparatus main body including an image readingportion; a rotating portion configured to be rotatable around a shaftwith respect to the apparatus main body, the rotating portion capable ofbeing placed at a first position, a second position where a rotationangle is more than that at the first position, and a third positionwhere the rotation angle is more than that at the second position; aholding portion configured to maintain the rotating portion at the firstposition; and a biasing portion configured to apply a force to move therotating portion from the first position to the second position when themaintaining of the rotating portion at the first position by the holdingportion is released.
 36. An image forming apparatus comprising: an imageforming portion configured to form an image on a recording medium; anapparatus main body including an image reading portion; a rotatingportion configured to be rotatable around a shaft with respect to theapparatus main body, the rotating portion capable of being placed at afirst position, a second position where a rotation angle is more thanthat at the first position, and a third position where the rotationangle is more than that at the second position; a holding portionconfigured to maintain the rotating portion at the first position; afirst biasing portion configured to apply a force to the rotatingportion such that the rotating portion is stoppable at a predeterminedposition, in a state in which the rotating portion is placed in a rangefrom the second position to the third position; and a second biasingportion configured to apply a force to move the rotating portion fromthe first position to the second position when the maintaining of therotating portion at the first position by the holding portion isreleased.